program main

    use region_type_m, only: region_t
    use math_m, only: rp, get_distance
    use internal_force_m, only: internal_force_without_visc
    implicit none

    type(region_t) :: region
    real(rp) :: acc(2, 9)
    integer :: i

    call region%set_data()
    call internal_force_without_visc(region, acc, 9)

    !> 打印结果
    print *, acc(:, 6)

end program main
